1. Field of the Invention
The present invention relates to a semiconductor device having an improved interlayer adhesiveness in an interlayer insulating film.
2. Related Art
Needs for achieving faster operation of semiconductor devices are growing in recent years, and in order to meet the needs, technologies for providing a metal interconnect with copper to reduce the interconnect resistance are widely employed. Such interconnect structure is formed via a damascene process including a chemical mechanical polishing (CMP) process.
When a damascene copper interconnect is formed, it is essential to provide an etch stopper film for forming an interconnect trench and/or a through hole, or a protective film for inhibiting the damage to the interlayer insulating film occurred during the chemical mechanical polishing (CMP) process. However, when such etch blocking film and/or protective film is employed, sufficient adhesiveness with other insulating films may not be obtained, and thus there is a room for the improvement.
Such problem concerning the adhesiveness becomes to be particularly considerable when an insulating material having lower dielectric constant is employed as a material for the interlayer insulating film. In most recent days, an investigation for reducing a capacitance among the interconnects is actively conducted, by replacing the material for the interlayer insulating film from the conventional silicon oxide film (dielectric constant K is approximately 4.3) to a low dielectric constant material having a dielectric constant of equal to or lower than 3.0. Although the use of such low dielectric constant insulating material for the interlayer insulating film reduces the crosstalk between the interconnects to allow achieving faster operation of the device, insufficient adhesiveness with the etch stopper film and/or the protective film may be presented. The problem concerning the adhesiveness becomes considerable when a SiOC film formed via a chemical vapor deposition (CVD) (hereinafter referred to as “CVD-SiOC film”) or a porous film is employed.
Investigations for improving the adhesiveness of the interlayer insulating film are conducted in various ways. For example, the assignee of the present application discloses in Japanese Patent Laid-Open No. JP-A-2001-326,222 that a technology for improving the adhesiveness by suitably selecting the material for the films is proposed.